Published 6 issues per year
ISSN Print: 1948-2590
ISSN Online: 1948-2604
EFFECTS OF TRANSITION PROCESSES ON SYSTEMATIC ERRORS OF HEAT MEASURING IN WIND TUNNELS
ABSTRACT
A procedure to estimate the heat flux density is presented based on results of temperature measurements using an elementary thin-film sensor. It is shown that the heat flux density cannot be measured but can be determined by means of convolution of the corresponding impulse transfer function with the time derivative from the temperature measured inside the sensor. Well-behaved analytic expressions of the impulse transfer functions are obtained using the inverse Laplace transformation of the inverse heat transfer problem, and a numerical solution method for short time periods is presented, with a provision for transition processes. Systematic errors are estimated, which depend on the main similarity parameters and the number of experiments.